Hydraulic fluid power systems are used to operate a variety of machinery. Hydraulic systems transmit and control power for operating machinery by forcing water, oil, or other liquid under pressure through an enclosed circuit of fluid conducting lines. Hydraulic jacks, tools for applying torque, and other hydraulic tools and machinery may be operated at high fluid pressures, typically in the neighborhood of 10,000 psi.
Fluid couplings for the hydraulic lines supplying power to tools and machinery typically comprise two primary components, or members: a generally cylindrical socket having an axial fluid flow passage that is attached to one hydraulic line and a generally cylindrical plug also having an axial fluid flow passage that is attached to the other. The plug is inserted into the socket to join the two lines and to create a single fluid flow passage between the lines. The coupling may be freestanding or the plug or the socket may be mounted in a manifold or wall or otherwise secured within the tool or machinery.
For many years, the socket and plug for couplings typically used in high pressure hydraulic tools and machinery have been secured in coaxial coupled relation by means of a cylindrical threaded sleeve that is threadedly fixed to the socket. The mating plug is provided with mating threads so that when the plug and socket are coupled, the operator secures the coupling by screwing the sleeve down onto the plug. The threaded sleeve provides a secure coupling, especially at high fluid pressures. However, securing the plug in this manner can be somewhat time consuming and the operator frequently must use tools. Also, tool and machinery operators sometimes wear heavy or bulky rubber gloves that become oily in use and reduce the dexterity with which the threaded sleeve can be manipulated.
Quick-action couplings sometimes are used as an alternative to couplings having threaded sleeves to more quickly join or separate fluid conducting lines without the use of tools or special equipment. Generally speakinq, the quick-action socket has a plurality of evenly spaced locking balls contained in apertures that form a circle around the plug receiving end of the socket. A spring biased detent sleeve circumscribing the socket holds the locking balls radially inwardly. To insert the plug into the socket, the operator first uses one hand to pull the detent sleeve longitudinally away from the plug receiving end of the socket so that the balls are released. Using the other hand, the operator inserts the plug into the socket. The plug has an annular groove to receive the locking balls. The operator then releases the detent sleeve, which holds the balls in the annular groove in the plug and secures the plug in the socket. The operator removes the plug from the socket in an analogous fashion.
The quick-action couplings described above have several disadvantages that detract from their usefulness. For example, the operator pulls the sleeve against the bias of a spring so that the plug can be inserted into and withdrawn from the socket. The coupling requires the operator to use both hands to manipulate the detent sleeve and to insert the plug into the socket. Using both hands in this manner reduces the speed with which the socket and plug can be connected and disconnected. The problems caused by using both hands are compounded if the operator is wearing gloves or the coupling is installed in a relatively inaccessible portion of a tool or piece of machinery.
Quick-action couplings adapted for assembly and disassembly with one hand have been available in the past, but these couplings typically are not suitable for use in high pressure hydraulic equipment. For example, U.S. Pat. No. Re. 23,120 to C. E. Earle et al. and U.S. Pat. No. 2,377,812 to A. T. Scheiwer disclose such snap couplings. These patents both disclose a spring-biased detent-actuating sleeve carried by a socket. The mating plug engages a detent operator, or plunger, to bias the sleeve to actuate the detent. The detent operator is mounted on the socket with the sleeve for engagement by the plug. The diameter and length of such a fitting substantially limit its use in areas of confined space, such as the interior of a high pressure hydraulic tool.
It would be desirable to provide a quick-action hydraulic coupling that is compact and suitable for use in areas of limited access. Such a coupling should not require the operator to use one hand to pull back the detent sleeve while inserting the plug into the socket with the other hand. Such a coupling could be useful in high pressure hydraulic equipment where space is limited.